In the past decade, digital imaging capabilities have been integrated into a wide range of devices, including digital cameras and mobile phones. Recently, the ability to capture stereoscopic images with these devices has become technically possible. Device manufacturers have responded by introducing devices integrating multiple digital imaging sensors. A wide range of electronic devices, including mobile wireless communication devices, personal digital assistants (PDAs), personal music systems, digital cameras, digital recording devices, video conferencing systems, and the like, make use of multiple imaging sensors to provide a variety of capabilities and features to their users. These include not only stereoscopic (3D) imaging applications such as 3D photos and videos or movies, but also higher dynamic range imaging and panoramic imaging.
Devices including this capability may include multiple imaging sensors. For example, some products integrate two imaging sensors within a digital imaging device. These sensors may be aligned along a horizontal axis when a stereoscopic image is captured. Each camera may capture an image of a scene based on not only the position of the digital imaging device but also on the imaging sensors physical location and orientation on the camera. Since some implementations provide two sensors that may be offset horizontally, the images captured by each sensor may also reflect the difference in horizontal orientation between the two sensors. This difference in horizontal orientation between the two images captured by the sensors provides parallax between the two images. When a stereoscopic image pair comprised of the two images is viewed by a user, the human brain perceives depth within the image based on the parallax between the two images.
In some environments, the primary use of an imaging device including multiple imaging sensors may still be to capture traditional two dimensional snapshots and movies. In these environments, use of the dual imaging sensors for stereoscopic images and movies may be considered a convenience feature that is less frequently used. For these users, an imaging device may be designed that provides one imaging sensor with a relatively high resolution. This first imaging sensor may be employed to capture two dimensional snapshots and movies. Since two dimensional images can be captured using only one imaging sensor, high quality two dimensional images using the one relatively high resolution sensor may be provided. The imaging device may also include a second imaging sensor, which captures images at a lower resolution than the first imaging sensor. This second imaging sensor may be used in conjunction with the first imaging sensor to capture image pairs for stereoscopic snapshots and movies. Since these stereoscopic image pairs include two images captured at different resolutions, additional image processing within the imaging device may compensate for the differences between the images captured by the two imaging sensors to provide the user with a satisfactory stereoscopic snapshot or movie.
Using two imaging sensors with different resolutions may reduce the cost of the imaging device when compared to an imaging device designed with two high resolution sensors. The cost reduction may be attributed not only to the lower cost of the second, lower resolution imaging sensor, but also to lower cost supporting electronics for the lower resolution sensor including, for example, power circuitry and image processing circuitry.
When imaging sensors with differing resolutions are utilized to capture a stereoscopic image pair, image processing methods employed by the imaging device may compensate for asymmetric sensor resolutions along with other differences that may exist between the two imaging sensors. For example, these methods may compensate for differences in the sensor geometry, brightness, and color response. Additionally, compensating for differences in the electronic timing and synchronization of the disparate sensors may also be necessary. Camera calibration methods may also be adapted to better calibrate the disparate imaging sensors.